JPH0351134A - Ink jet recording head - Google Patents

Abstract

PURPOSE:To eliminate a structural complexity and increase the density of nozzle positions by setting temperature in two stages by application of pressure to sublimable ink. CONSTITUTION:A heater 3 is provided near each nozzle 8 and an ink temperature near the nozzle 8 is increased to the first maintained temperature T1. Ink 2 is liquid 5 under pressure and is pressed out to the opening of the nozzle 8. If the ink is pressed like this, the ink 2 is returned to a state at one atmospheric pressure from the pressurized state. Therefore, the ink 2 becomes solid 6, which is a state where an action is ready, so that the sublimable ink is heated to the second maintained temperature T2 by a heater 3 in accordance with a recording instruction signal. The ink 2 thus evaporated becomes sublimated and then is ejected as a gasified ink 7 from the nozzle 8. In this way, ink droplets are discharged selectively from the nozzles 8 using a signal from a head drive section to form a recorded image with the ink 2 on a recording medium. Consequently, an ink jet recording head with a fully multiple nozzle function is obtained. the head is of a simple structure and free from clogging.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an on-demand inkjet head that prints characters, graphics, etc. by ejecting ink vapor in accordance with image signals to form dots on a recording medium. .

BACKGROUND OF THE INVENTION Conventionally, various methods have been devised for inkjet heads, which are a means of ink recording technology, and sublimable dyes have been used as a means for ejecting ink in on-demand inkjet heads. is publicly known. For example, it is disclosed in Japanese Patent Application Laid-open No. 61-106258 and Japanese Patent Application Laid-open No. 61254351.

An example of the structure of a conventional inkjet head is shown in FIGS. 3 and 4. First, in FIG. 3, ink 2 which is solid at room temperature is put into an ink chamber 1, fluidized or sublimated by a heater 12, and the vaporized ink 17 is pressurized by a piezo element 14 and jetted from a nozzle 18.

In the example shown in FIG. 4, the solid ink 2 is installed in the ink chamber 1, and the heater 13 is heated by the heater drive device 23 in accordance with a recording signal to sublimate the solid ink 2. The vaporized ink is ejected from the nozzle section 18 by the flow of air from the air supply section 19.

Problems to be Solved by the Invention All of these conventional inkjet recording devices have complicated structures and have a plurality of nozzles (16/16).
It is impossible to arrange them at a high density of about 1 m.

The present invention eliminates the structural complexity that is a drawback of the prior art, enables high-density multi-nozzle arrangement, and enables recording of one line at a time by arranging a plurality of nozzles corresponding to orders of magnitude. Aiming to realize an inkjet recording head with a fully multi-structure This solves the above problem.

Effect of the present invention With the above structure, the sublimable ink is liquefied under pressure at the first holding temperature (Fig. 2B), and at the nozzle opening, it is released from pressure compression and becomes 1 atm, so it returns to a solid state. (
Fig. 2C), then from the above state, the area near the nozzle is
By raising the temperature to the holding temperature, the solid ink sublimes (FIG. 2D) and is ejected from the nozzle. Such an action makes it possible to record ink on a recording medium with a simple structure without clogging the nozzle portion with ink.

Example Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1(a) is a schematic cross-sectional view of an inkjet head according to an embodiment of the present invention, and FIG. 1(b) is a partial top view thereof. The configuration and operation will be explained below with reference to the temperature state diagram shown in FIG. In FIG. 1(a), reference numeral 1 denotes a head structure, in which sublimable solid ink is placed as ink 2 in a container 10 having a nozzle 8, and a spring 4
Pressure is always applied in the right direction in the figure. The ink 2 is in a solid state as shown in A in FIG. The entire head assembly 1 is preheated by a heater 9 and set to a temperature slightly lower than the first holding temperature TI, and the state of the ink 2 is maintained in a solid phase.

A plurality of nozzles 8 are arranged as shown in FIG. 1(b). In this example, the arrangement density is 16 pieces/■, and the opening diameter is 3.
0 μmφ, 3,200 nozzles, and 20 full multi-heads with a width of 1 m, but the conditions are not limited to these.

A heater 3 is provided near each nozzle 8 to raise the ink temperature near the nozzle 8 to a first holding temperature Tl.

In the pressurized state, the ink 2 becomes a liquid ink state 5 (B in FIG. 2) and is pushed out into the opening of the nozzle 8. Nozzle 8
When the ink 2 is pushed out to the opening of
)become. In this state, when the operation is ready, if the heater 3 heats the sublimable ink to the second holding temperature T2 according to the recording instruction signal, it will be vaporized as shown in D in FIG. The ink is sublimated and injected as a gaseous ink 7. With such a function, ink droplets are selectively ejected from each nozzle 8 in response to a signal from the head driving section, and the ink 2 adheres to a recording medium (not shown) to form a recorded image.

Note that the overall preheating heater 9 used in this embodiment is not always necessary.

Effects of the Invention As described above, the present invention realizes a fully multi-nozzle inkjet recording head with a simple structure and no nozzle clogging by pressurizing sublimable ink and setting the temperature in two stages. did it.

[Brief explanation of drawings]

1(a) and 1(b) are a cross-sectional view and a front view showing the structure of an inkjet head in an embodiment of the present invention, and FIG.
The figure is a temperature diagram of the sublimable ink used in the present invention, and FIGS. 3 and 4 are cross-sectional views showing the structure of a conventional inkjet head using the sublimable ink, respectively. Tohenodo structure, 2... ink, 3... heater, 4.
Spring, 5...Liquid ink state, 6...Solid ink state, 7. Gas ink, - Nozzle, 9. Heater, 10.. Container.

Claims (3)

[Claims] (1) A container having a nozzle opening and containing sublimable ink, means for pressurizing the sublimable ink, and a heater disposed near the nozzle opening, and the sublimable ink is heated by the heater. An inkjet recording head characterized in that a first temperature and a second temperature are set sequentially. (2) The inkjet recording according to claim 1, wherein the first temperature is a temperature at which the sublimable ink is solid at 1 atmosphere and becomes liquid under pressure, and the second temperature is a temperature at which the sublimable ink is a gas at 1 atmosphere. head. (3) The inkjet recording head according to claim 1, further comprising a second heater that heats the entire inkjet recording head to maintain the entire inkjet recording head at a temperature equal to or lower than the first temperature.